Brake mechanism



March '29, 1949. J. G. oE'rzEL 2,465,394

BRAKE MEcHANIsu l Filed Dec. 29, 1944 4 sheets-sheet 2 CVO/w GeorgeOeje/ f4, CMA, fw 7.4M, 0.1

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l J. s. oE'rzEL BRAKE MEcmmIsu I Nimh 29, 1949.

'4 .sheets-Sheet 3 Filed Dec. 249, 1944 ml Jmlf/ Patented Mar. 29, 1949BRAKE MECHANTSM John George Oetzel, Beloit, Wis., assignor to WarnerElectric Brake Manufacturing Company, South Beloit, lll.. a corporationof Illinois Application December zo, 1944, serial No. 570,277"

4 claims. i

This invention relates generally to friction brake mechanisms of thecharacter used on vehicle wheels and in certain aspects has moreparticular reference to brakes of the compound type wherein an auxiliaryexpandable friction element derives an actuating force to expand a mainfriction element.

One vobject of the invention is to provide a novel arrangement of themain and auxiliary friction elements to provide a powerful -brakingtorque and extreme axial compactness in a brake mechanism of the abovecharacter.

Another object is to provide a vnovel anchor construction.

Other objects and advantages of the invention will become apparent fromthe following detailed description taken in connection with theaccompanying drawings, in which Figure l is a diametrical sectional viewof a brake embodying the novel features of the present invention, thesection being taken alongthe line I-I of Fig. 3.

Figs. 2 and 3 are sections taken respectively along the lines 2-2 and3-3 of Fig. l.

Fig. 4 is a perspective view of the main anchor member.

While the invention is susceptible of various modifications andalternative constructions. I have shown in the drawings and will hereindescribe in detail the preferred embodiment. It is to be understood,however, that I do not intend to limit the invention by such disclosurebut aim to cover all modifications and alternative constructions fallingwithin the spirit and scope of the invention as expressed in theappended claims.

The brake mechanism shown for purposes of illustration is of theinternal expanding type adapted for use with a drum I having an inturnedange II bolted to the vehicle wheel I2 or other part to be braked andhaving an internal cylindrical surface I3 adapted to be gripped by themain or non-rotatable friction element of the brake mechanism. Thelatter is supported by an anchor member indicated generally at I4 andcomprising a casting (Fig. 4) having an inner peripheral flange I5bolted to a collar I6 which is splined onto the wheel axle I1 with theange I5 axially located centrally of the drum. Pro- .iecting outwardlyfrom diametrically opposite sides of the flange I5 are two pairs ofgenerally iiat arms I8 axially spaced apart and integrally connected bya web I9 at their outer ends which are disposed close to the drumsurface-- I3. Pairs oi' lugs 20 project from opposite siti es of thearms (ci. iss-13S) I8 and cooperate with the edge surfaces 2l t0 formflat abutment anchors for the ends of the main friction element.

Herein, this main element comprises two semicircular shoes 22 eitherflexible or rigid and arranged in end to end relation and havingsegments 23 of suitable friction. material secured to their outersurfaces. Brackets 24 at opposite ends of each shoe and on both sides ofeach shoe end bear against the abutment surfaces 2| and the lugs 20 andare normally held against the latter by return springs 25. The shoes arecentered with respect to the anchor and drum surface by lugs 26projecting from the center of each shoe end into the space between theanchor arms The friction element is expanded to apply the brake bymovement of the corresponding ends of each shoe 22. This is accomplishedby cam surfaces 21 bearing against the ends of the shoe lugs 25 andformed intermediate the ends of crank arms 28 which project inwardlyfrom their supporting p-ivot pins 29. There is a crank for each shoe endand the cranks` for each pair are disposed between the anchor arms I 8on opposite sides of the connecting web I9 which limits the swing ofeach crank toward the adjacent crank.

Actuation of two of the cranks 28 to move the corresponding shoe endsaway from released position and against their anchors at the oppositeshoe ends is eifectedby pins 30 projecting parallel to the drum axis inbetween the inner ends of the cranks 28 of the respective pairs. Thepins project through triangular holes 3| in the anchor arms and theother ends of the pins are anchored in an auxiliary anchor member in theform of a ring 32 which lies alongside 'the cranks 28 and extends aroundthe cylindrical hub 33 on which the ring is journaled for oscillationabout the drum axis. This hub is integral with the main anchor I4 andprojects toward the vehicle wheel I2 into an auxiliary drum 34concentric with the main drum Ill but also`terminating short of thecranks 28 which are on the center line of the main friction element. Theauxiliary drum has an inturned flange 42 secured to the wheel I2 bybolts 43.

The internal cylindrical surface 35 of this drum cooperates with anauxiliary friction element comprising two shoes 36 having frictioncoverings V31 and arranged end-to-end with the'adjacent Expansion of theauxiliary friction shoes 2l is eifected in the present instance by amomentum operator whose parts are concentric with the anchor ring 22 andthe auxiliary drum 24. The operator includes an annular magnet ring umounted to osciliate on a cylindrical surface 4I of the auxiliary anchorring and back by an outwardly projecting nange I2! thereon. i The magnetis of U-shaped cross-section having concentric poles enclosing a windingIt and terminating in end faces spanned by an armature ring Il. Thelatter is supported by tangentially extending leaf springs 4I fastenedto the wheel I2 by the bolts 42, the springs also serving to maintaincontinuous mechanical contact between the armature and the face of themagnet. Lugs 4I project rigidly from the outer magnet pole into thespace between the spaced parts of the anchor arms Il and are of the samecircumferential length as these arms. The lugs are thus positioned forengagement with the ends 3l of the auxiliary 'shoes and are operable tomove one or the other ends of these shoes away from their anchors Ilwhen the magnet is turned in either direction. .i

Rieturnof the magnet 44, the actuated ends of the auxiliary shoes 2l andthe auxiliary anchor ring I2 to normal brake-released position iseffected by springs 4l stretched between the shoes It and brackets Il onthe magnet, springs l stretched between the magnet and eyes 50' on theanchor ring 32. and springs Slib (Figs. 1 and 3) acting between the ringI2 and the main anchor II.

When the magnet Il is deenergized, the parts are disposed in thepositions shown in the drawings. the brake then being released.Energization of the magnet winding produces proportional grippingengagement between the rotating armature 41 and the friction face of themagnet causing the latter to turn with the wheel. This movement iscommunicated through the actuating lugs Il to the corresponding ends `Ilof the auxiliary shoes Il which are thereby expanded against the drum24. The resulting friction force applied to these shoes urges them andtheir floating anchor ring l2 in the direction of drum rotation therebymoving the actuating pins Il to swing two of the cranks 2l and therebymove the corresponding ends of the main brake shoes 22 away from theiranchors.

After these shoes engage the surface I3 of the main drum, slippageoccurs between all of the coacting friction surfaces and a powerful reltarding torque is exerted on the wheel. 'I'his torque is the result ofself-energizing forces produced by the magnet and armature, thenampliiled by the auxiliary friction element, and finally applied to themain friction element. By augmenting the initial actuating force in thisway. the desired resultant retarding torque is obtained withoutsacrificing ccmtrollability in accordance with the energization of themagnet winding. When the latter is deenergized. the parts are returnedquickly to their brake-released positions by the action of the springs25, 40, Il. and SIb.

It will be observed that all of the parts of the main. auxiliary andmagnetic operators are compactly arranged within a comparatively narrowannular space between the drum III and the hub 33. Also, by disposingthe auxiliary brake mechanism, which may be made of relatively shortaxial length. within the main brake and to one side of the center of thelatter, the over all axial length of the compound brake is reduced to aminimum. This arrangement also permits the use of relatively long crankarms 2l and their location on the center lines of the main brake shoes.

I claim as my invention:

l. A brake mechanism having. in combination, a main anchor member havingan axially projecting hub and a plurality of angularly spaced stopsdisposed outwardly beyond said hub and each having circumferentiallyspaced abutment surfaces facing circumferentially in oppositedirections, lan annular friction element having a plurality of partswith their ends abutting said surfaces and separable therefrom to expandthe element, crank means mounted on said stops to swing in the plane ofthe center line of said eiement and projecting inwardly to a positionadjacent said hub and engageable with said element ends, a second anchormember journaled on said hub externally thereof and plvotally connected`to the inner ends ofsaid crank means whereby to move the correspondingelement ends away from their stops and expand the element when theauxiliary anchor is turned in either direction away from a normalbrake-released position, a second annular friction element of smallerradius than and less than half the width of said first element supportedby said second member between said nrst element and said hub anddisposed between said plane of the center line of said first element butaxially offset from the latter so as to lie alongside said crank means.said second element having circumferentially separable ends adapted forabutting engagement with stop surfaces on said second member, a ringsmaller thansaid second element and journaled on said second anchormember in the plane of the second element to turn about the'axls of isaid hub, and means connecting said` ring and the ends of said secondelement and operable selectively to move either one or the other of suchends away from its stop and thereby expand the element upon turning ofthe ring in either direction away from brake-released position, saidsecond friction element, when expanded into engagement with a rotatingdrum surface, causing angular movement of said second anchor member andactuation of said crank means thereby.

2. A brake; mechanism having, in combination, a main anchor memberhaving an axially projecting hub and a stop disposed outwardly beyondsaid hub and having circumferentially spaced abutment surfaces facingcircumfer` entially in opposite directions, an annular frictionelementhaving ends abutting said surfaces and separable therefrom toexpand the element,- inwardly projecting crank means mounted on saidanchor member to swing in the plane of the center line of said elementand engageable selectively with either one or the other of said elementends to move such end away from its abutment surface, a second anchormember t journaled on said hub externally thereof and plvotallyconnected to the inner end of said crank means whereby to move thecorresponding element ends awayfrom anchors and expand the element whenthe auxiliary anchor is turned in either direction away from a normal4brake-released position, a second friction element substantiallynarrower and of smaller radius than said first element supported by saidsecond member between said first element and was,

said hub and disposed between said plane of the center line of saidiirst element but axially oiset from the latter so as to lie alongsidesaid crank means, said second element having circumferentially separableends anchored on said second member, and actuating means movablymountedon said second anchor member to turn about the `axis oi? said hub ineither direction away from a normal brake-released position and operablein such movement to move one or the other of the endsv of said secondelement away from its anchor and expand the latter, said second frictionelement,`when expanded into engagement with a rotating drum surface,causingangular movement of said second anchor mem- -ber and actuation ofsaid crank means thereby.

3. A brake mechanism having, in combination, inner and outer annularradially expansible friction elements having cylindrical peripheralsurfaces concentric with each other, the inner element being narrowerthan the outer element and offset axially from the center line of thelatter element, a non-rotatable anchor for the outer element, an anchorfor the inner element movable about the axis of the elements, means forexpanding said inner element, and operating means connecting saidmovable anchor and said outer element and operable to expand the latterupon turning of the anchor in either direction away from a normalbrakereleased position, said inner friction element, when expanded intogripping engagement with a rotating drum surface causing angular move#ment of said inner element anchor and actuation of said operating meansthereby, and said operating means being disposed alongside said innerelement and having all of its parts movable in the central plane of saidouter element.

4. A brake mechanism having, in combination, inner and outer annularradially expansible friction elements having cylindrical peripheralsurfaces concentric with each other, the inner element being narrowerthan the outer element Number movable about the'axis of the elements,means for expanding said inner element, operating means connecting saidmovable anchor and said outer element and operable to expand the latterupon turning of the anchor in 4'either direction away from a normalbrake-released position, said operating means being disposed alongsidesaid inner element and havingall of its parts movable in the centralplane of said outer element, a ring mounted to oscillate about lsaidaxis and disposed in the plane of the center line of said inner element,and means connecting said inner element and said ring for expanding thelatter upon turning of the ring in either direction from a normalbrake-released position, all of the parts of said last mentionedconnecting means lying in the plane of the center line of said innerelement, said inner .Iriction element, when expanded into grippingengagement with a rotating drum surface causing angular movement of saidinner element anchor and actuation of said operating means thereby.

JOHN GEORGE OETZEL.

REFERENCES CITED The following references are of record in the ille ofthis patent:

UNITEDSTATES PATENTS FOREIGN PATENTS Country Date France Sept. 11, 1933France May 13, 1935 Number

